5 ms·

I caught a little bit of traffic earlier tonight on the downlink frequency, but I wasn't able to contact anybody myself. Possibly if I'd realized the ISS was in

I caught a little bit of traffic earlier tonight on the downlink frequency, but I wasn't able to contact anybody myself. Possibly if I'd realized the ISS was in the vicinity and gone outside earlier I would have had a shot (I only have an HT radio at the moment), but by the time I got out there they were somewhere over the North Atlantic. The ISS, if you didn't realize, moves pretty fast. Oh well, there's always next time.

bigiain 6y ago
What sort of antenna would I need to listen in with a rtl-sdr? Would I have any chance with a simple home built 1/2 wave dipole?
- GekkePrutser 6y ago
  Yes I've received it on a portable even. For a satellite it's easy probably because they're so close (LEO) and have plenty of power too burn.
  - tomfanning 6y ago
    Yeah, it's a lightly modified Kenwood mobile VHF/UHF set typically used in a car. Model D710GA. Stock it's a 50W radio, though can be run at 5W. Cube sats have around the hundreds of milliwatts. So yes, much higher power than a cube sat.
    - mindcrime 6y ago
      Some more info on the equipment being used: https://www.jvckenwood.com/en/press/2020/03/press_200313_2.html https://www.jvckenwood.com/en/press/2020/03/press_200313_2.h...
    - deleted 6y ago
      [deleted]
- mindcrime 6y ago
  I was able to hear some of the traffic using my Baofeng F8HP with a stock rubber ducky antenna, so you don't need much on the receive side. At least when the ISS is close to you. Not sure what the window is as far as how far removed it can be from directly overhead, and yet still be able to receive that signal with a small antenna like that. What it takes to hit the repeater I'm less sure. I've heard it can be done with an HT like mine, but I'm guessing that's only possible when it's directly overhead, or very near so. That said, I'd be happy to find out that I'm wrong about that.
- signaturefish 6y ago
  I believe you can hit it with an HT, although the Youtube videos I've seen of doing it have been an HT with a hand-held Yagi cabled in in place of the usual whip antenna. A resonant dipole would probably pick it up - as others have said, the signal's fairly powerful. Satellite comms is something I want to play with, personally, so I welcome this news. Need to get my Foundation license (UK) before I can go two-way, though.
  - jimnotgym 6y ago
    Go for it! It really isn't hard, it just requires a small amount of application.
- tmostak 6y ago
  Definitely can pick it up with a HT, just caught it for ~3 minutes in the Bay Area on a Baofeng HT with whip antenna, and even picked up the first part while I was still indoors. There was a lot of static although I could make out some of the sentences.
  - signaturefish 6y ago
    Wow, that's a stronger signal than I thought. Maybe I'll give it a go with a whip the next time the ISS passes over me.
- tomfanning 6y ago
  For listening, a QFH antenna is ideal for LEO objects. It's typically made of copper pipe or the braid of stiff coax.
- jimnotgym 6y ago
  Absolutely you will do well with a dipole.
acqq 6y ago
> The ISS, if you didn't realize, moves pretty fast. I waited a few times to see it, and it's always just a few minutes it's visible. It orbits low and makes the full cycle around the globe in only 90 minutes.
- Shacklz 6y ago
  For those curious when and where to look to see the ISS by eye only: https://james.darpinian.com/satellites/ https://james.darpinian.com/satellites/ The site is incredibly awesome and helped me see the ISS (and other satellites) quite a few times already!
  - Moru 6y ago
    Stellarium is great for this too.
- sgt 6y ago
  I recommend the app ISS Spotter by Martin van Mierloo.
- tomfanning 6y ago
  A 90 degree pass (overhead) is around 10 minutes. And obviously for radio, it doesn't need to be visible (reflecting sunlight), just ~above the horizon.
  - acqq 6y ago
    > A 90 degree pass (overhead) is around 10 minutes. Yes, that's approximately what I remember. The path of ISS is created with the goal that ISS doesn't fly over the same pieces of land or sea. Instead, it takes a lot of orbits before I can see it crossing exactly over my location, giving me around 10 minutes when that cross is ideal, otherwise, it's less, if the current path is close enough at all. Seeing is of course limited more than obtaining a radio signal, as to see ISS it has to fly above you at the time that the sun can reflect from it, and to have clear skies. One doesn't need that to catch just a radio signal, but the ISS path should still be such that it's close to your location, and the time during the FM signal can be received will still be short.
tomfanning 6y ago
Sounds like you're already on it, but anyone who is thinking of trying, (1) make sure you are correctly licensed, (2) make sure you only transmit while you can clearly hear the downlink, and (3) make sure you are listening to the downlink while transmitting (full duplex) to ensure you aren't stepping on other people.
- mlyle 6y ago
  > (3) make sure you are listening to the downlink while transmitting (full duplex) to ensure you aren't stepping on other people. If possible. Not everyone has fancy-pants cross-band full duplex capability. I know a couple HTs will do it now, but this is still a bit exotic. This is the strongest space amateur FM repeater ever; surely those of us who are better equipped can use SO-50, etc, without issue, and we shouldn't get too mad if there's a little less-than-ideal operation on something as newbie-friendly as this.
  - dx4100 6y ago
    My cheapest HT can do this. And my 20 year old radio can do it. So not sure about "exotic"
    - jimnotgym 6y ago
      What radios are they?
      - nickysielicki 6y ago
        Kenwood's TH-D72, TH-V71A, and TM-D710G can do it. An incomplete list of full duplex vhf/uhf cross-band FM radios can be found in this reddit comment: https://www.reddit.com/r/amateurradio/comments/97jhik/getting_into_satellites_need_full_duplex_uhfvhf/e48mxpf/?context=3 https://www.reddit.com/r/amateurradio/comments/97jhik/gettin...
        jimnotgym 6y ago

bigiain 6y ago

What sort of antenna would I need to listen in with a rtl-sdr? Would I have any chance with a simple home built 1/2 wave dipole?

GekkePrutser 6y ago
Yes I've received it on a portable even. For a satellite it's easy probably because they're so close (LEO) and have plenty of power too burn.
- tomfanning 6y ago
  Yeah, it's a lightly modified Kenwood mobile VHF/UHF set typically used in a car. Model D710GA. Stock it's a 50W radio, though can be run at 5W. Cube sats have around the hundreds of milliwatts. So yes, much higher power than a cube sat.
  - mindcrime 6y ago
    Some more info on the equipment being used: https://www.jvckenwood.com/en/press/2020/03/press_200313_2.html https://www.jvckenwood.com/en/press/2020/03/press_200313_2.h...
  - deleted 6y ago
    [deleted]
mindcrime 6y ago
I was able to hear some of the traffic using my Baofeng F8HP with a stock rubber ducky antenna, so you don't need much on the receive side. At least when the ISS is close to you. Not sure what the window is as far as how far removed it can be from directly overhead, and yet still be able to receive that signal with a small antenna like that. What it takes to hit the repeater I'm less sure. I've heard it can be done with an HT like mine, but I'm guessing that's only possible when it's directly overhead, or very near so. That said, I'd be happy to find out that I'm wrong about that.
signaturefish 6y ago
I believe you can hit it with an HT, although the Youtube videos I've seen of doing it have been an HT with a hand-held Yagi cabled in in place of the usual whip antenna. A resonant dipole would probably pick it up - as others have said, the signal's fairly powerful. Satellite comms is something I want to play with, personally, so I welcome this news. Need to get my Foundation license (UK) before I can go two-way, though.
- jimnotgym 6y ago
  Go for it! It really isn't hard, it just requires a small amount of application.
tmostak 6y ago
Definitely can pick it up with a HT, just caught it for ~3 minutes in the Bay Area on a Baofeng HT with whip antenna, and even picked up the first part while I was still indoors. There was a lot of static although I could make out some of the sentences.
- signaturefish 6y ago
  Wow, that's a stronger signal than I thought. Maybe I'll give it a go with a whip the next time the ISS passes over me.
tomfanning 6y ago
For listening, a QFH antenna is ideal for LEO objects. It's typically made of copper pipe or the braid of stiff coax.
jimnotgym 6y ago
Absolutely you will do well with a dipole.

acqq 6y ago

> The ISS, if you didn't realize, moves pretty fast. I waited a few times to see it, and it's always just a few minutes it's visible. It orbits low and makes the full cycle around the globe in only 90 minutes.

Shacklz 6y ago
For those curious when and where to look to see the ISS by eye only: https://james.darpinian.com/satellites/ https://james.darpinian.com/satellites/ The site is incredibly awesome and helped me see the ISS (and other satellites) quite a few times already!
- Moru 6y ago
  Stellarium is great for this too.
sgt 6y ago
I recommend the app ISS Spotter by Martin van Mierloo.
tomfanning 6y ago
A 90 degree pass (overhead) is around 10 minutes. And obviously for radio, it doesn't need to be visible (reflecting sunlight), just ~above the horizon.
- acqq 6y ago
  > A 90 degree pass (overhead) is around 10 minutes. Yes, that's approximately what I remember. The path of ISS is created with the goal that ISS doesn't fly over the same pieces of land or sea. Instead, it takes a lot of orbits before I can see it crossing exactly over my location, giving me around 10 minutes when that cross is ideal, otherwise, it's less, if the current path is close enough at all. Seeing is of course limited more than obtaining a radio signal, as to see ISS it has to fly above you at the time that the sun can reflect from it, and to have clear skies. One doesn't need that to catch just a radio signal, but the ISS path should still be such that it's close to your location, and the time during the FM signal can be received will still be short.

tomfanning 6y ago

Sounds like you're already on it, but anyone who is thinking of trying, (1) make sure you are correctly licensed, (2) make sure you only transmit while you can clearly hear the downlink, and (3) make sure you are listening to the downlink while transmitting (full duplex) to ensure you aren't stepping on other people.

mlyle 6y ago
> (3) make sure you are listening to the downlink while transmitting (full duplex) to ensure you aren't stepping on other people. If possible. Not everyone has fancy-pants cross-band full duplex capability. I know a couple HTs will do it now, but this is still a bit exotic. This is the strongest space amateur FM repeater ever; surely those of us who are better equipped can use SO-50, etc, without issue, and we shouldn't get too mad if there's a little less-than-ideal operation on something as newbie-friendly as this.
- dx4100 6y ago
  My cheapest HT can do this. And my 20 year old radio can do it. So not sure about "exotic"
  - jimnotgym 6y ago
    What radios are they?
    - nickysielicki 6y ago
      Kenwood's TH-D72, TH-V71A, and TM-D710G can do it. An incomplete list of full duplex vhf/uhf cross-band FM radios can be found in this reddit comment: https://www.reddit.com/r/amateurradio/comments/97jhik/getting_into_satellites_need_full_duplex_uhfvhf/e48mxpf/?context=3 https://www.reddit.com/r/amateurradio/comments/97jhik/gettin...
      - jimnotgym 6y ago